The Cardiovascular System Flashcards
What are the 2 circulation loops?
Pulmonary circulation loop –> through the lungs to oxygenate. Systemic circulation loop –> through the body to oxygenate tissues and receive deoxygenated blood
What is the volume of blood in the body?
5L
What has the greatest surface area in the CVS?
Capillaries
Where is the majority of the blood found?
65% blood in peripheral veins
What is cardiovascular bridging?
compression (due to beating heart) of a segment of coronary artery during systole = narrowing that reverses during diastole
In what manner does the heart contract?
Contracts in helical manner
What are end arteries?
terminal artery that doesn’t have any secondary means of flow/no collateral circulation, if blocked very dangerous = central artery to retina
What is collateral circulation?
circulation that develops to bypass occlusion (stenosis) to maintain blood supply
Name the 4 values and the number of valve flaps
aortic (3), pulmonary (3), tricuspid (3), mitral (2)
List the stages of cardiac conduction
SA node: pacemaker. AV node: momentary pause of conduction at AV so stop simultaneous contraction = AV DELAY. Bundle of his. L/R bundle branch. Purkinje fibres
Where is the apex of the heart anatomically?
5th intercostal space
Where do the coronary arties branch from?
Aorta
What happens in systole?
Left ventricle contraction = BP in aorta to rise To 120mm Hg. Walls of elastic aorta (and other elastic arteries) stretch
What happens in diastole?
Aortic semilunar valve closes. Walls of aorta recoil, maintaining pressure on the blood + moving it towards heart + smaller vessels. Pressure drops to 70-80mm Hg
Define the term: capacitor vessel
elastic arteries act as pressure reservoir
What are the layers of the vessels?
Layers = tunica intima –> tunica media (elastin fibres) –> tunica adventitia
What is the main structural difference between arteries and veins?
Arteries = thick tunica media. Veins = valves
What is the most common site for an aneurysm and why?
most common site = intrarenal region of aorta due to drop in elastic fibre level = weaker vessels
How does vessel constriction take place?
neurotransmitter migrates through outer layer of vessel, reaches tunica media, layer with muscle fibres, cells are depolarised, depolarisation propagates to all cell via gap junctions = contraction
What is the name for the band of smooth muscle that adjusts blood flow into capillaries?
Precapillary sphincter
Where is blood velocity at its lowest and what benefit does this give?
Capillaries –> blood velocity is at its lowest = time for gas/nutrient exchange
How does venous blood return from the periphery?
Calf muscle pumping: skeletal muscle contraction, propagates blood back to heart. At rest: breath in, diaphragm down, intrathoracic pressure goes down, blood rushes to atrium. Valves in veins of lower limbs – no veins in intraabdominal, intrathoracic or neck veins
What is heart failure?
floppy L ventricle, blood pumped at reduced volume, due to hypertension, coronary arterial diseases, HA, cardiomyopathy = more blood volume in the LV but lower stoke volume
What causes pulmonary oedema?
LVF, left ventricular failure –> = pulmonary oedema = pooling in the ventricle, goes back into lungs, pressure in the blood vessels increases as volume increases, pressure pushes fluid into alveoli
What is starlings law of the heart?
Stroke volume of heart goes up in proportion to end diastolic volume = more you fill heart, better it contracts
What vessel has the largest diameter?
Vein
What vessels supply blood to the capillary bed?
Metarterioles
What is the main structure at the anterior of the heart?
R atrium, R ventricle
What is the main structure posterior on the heart?
L atrium, L ventricle
List the order of blood flow around the cardio-respiratory system
Superior/Inferior vena cava, right atria, tricuspid valve, right ventricle, pulmonary valve, pulmonary arteries, lungs, right and left pulmonary veins, left atria, mitral valve, left ventricle, aortic valve, aorta, arteries, arterioles, metarterioles, capillaries, post capillary venules, venules, veins –> back to superior/inferior vena cava.
What is a healthy BP?
120/80
